Effect Of Intramuscular Heat Stimulation In Treatment Of Urate-induced Arthritis And Its Spinal Cord Mechanisms-in Strategy Of "Left Disease-Right Treatment"

Acute gouty arthritis(GA)is a serious inflammatory disease,during which microcrystals of monosodium urate monohydrate(MSU)aggrades progressively in joint tissues including joint capsule,cartilage,and bursa synovialis.Studies have demonstrated that acupuncture and moxibustion are in effectively treating acute and or chronic pain.More recently,our series of studies provide a novel idea:non-painful heat stimulation,in effectively treatment of pain associated with corresponding diseases.Based on this novel concept,the present study was aimed to alleviate acute gout attack of arthritis pain by means of different temperatures and durations of i.m.heating-needle stimulation applied to 'Zusanli' acupoint,and explore the spinal cord associated mechanisms underlying strategy of left disease-right treatment.ObjectiveThe study was designed to investigate the effects and mechanism of i.m.heating-needle stimulation applied to 'Zusanli' acupoint in treatment of urate induced arthritis,so as to provide scientific basis for clinical treatment and usage.We further explored the potential neural mechanism within the spinal cord underlying strategy of left disease-right treatment.MethodsFive sets of experiments were arranged:(1)to establish the model of gout and urate-induced arthritis,(2)to explore effects of heating-needle applied to 'Zusanli' acupoint in treatment of urate induced arthritis,(3)to reveal potential spinal mechanism underlying the i.m.heating-needle stimulation associated with strategy of left disease-right treatment,(4)to observe influence of intrathecal(i.t.)injection of different opioid-s antagonists on the heating-needle acupoint stimulation,and(5)to detect histological expression of PGE2,IL-1 in blood and joint effusion in the treatment of urate-induced arthritis after the i.m.heating needle stimulation.In Experiment 1,rats were randomly divided into the following three groups(n=8 for per group):0.9%saline group,0.9%saline + Tween80 group,Urate group(25?l).Mechanical and heat stimuli were assessed on baseline before ankle joint cavity injection,1?7 days after injection,a hand-held electronic von Frey device(2290 Electrovonfrey,IITC Co.USA)with a rigid filament was used to detect the mechanical paw withdrawal threshold.Heat-evoked paw withdrawal responses were determined by means of a 390G plantar stimulator Analgesia Meter(IITC Co.USA).The swelling degree of ankle joint was detected by the foot swelling measuring instalment(IITC Co.USA).In Experiment 2,urate-injected rats were randomly divided into the following eight groups(n=8 for per group):Urate group,Urate + N.S.45min group,Urate + warm N.S.43?(15?30?45min)group,Urate + warm N.S.46?(15?30?45 min)group.Urate was injected into the right ankle after the baseline responses determined.One day;after the injection,a period of 15-45 min single heating-needle applied to 'Zusanli'acupoint stimulation at a temperature of either 43? or 46? were arranged,and a period of 45 min insertion of the needle without heating served as control.Procedures of behavior tests were the same as Experiment 1.In Experiment 3,urate-injected rats were randomly divided into the following five groups(n=8 for per group):Urate group,Urate + warm N.S.43?(ipsilateral,contralateral),Urate + warm N.S.46?(ipsilateral,contralateral)group.Urate was injected into the right ankle after the baseline responses determined,first days after injection were given heat treatment on one ipsilateral side and contralateral side heated needle applied to 'Zusanli' acupoint stimulation at a temperature of either 43? or 46?.Detect the animal nociceptive flexor reflex within 7 days after treatment,procedures of behavior tests were the same as Experiment 1.In Experiment 4,urate-injected rats were randomly divided into the following five groups(n=8 for per group):Urate group,0.9%saline group,intrathecal(i.t.)?-opioid receptor antagonist ?-FNA group,i.t.?-opioid receptor antagonist naltrindole group,i.t.?-opioid receptor antagonist nor-BNI group.All antagonists were dissolved in 0.9%saline.Given the i.m.43? heating-needle stimulation at the first day after urate-injected.in second days,detection in 0.5,1,2,3,4h after the intrathecal(i.t.)injection of 0.9%saline and different opioid receptor antagonists.Procedures of behavior tests were the same as Experiment 1.In Experiment 5,this experiment comprised two sub-experiments.In sub-experiment 1,urate-injected rats were randomly divided into the following three groups:Urate group,Urate + N.S.45 min group,Urate + warm N.S.43? 30 min group.Urate was injected into the right ankle after baseline determined,the first day after the injection given the 30 min single heating-needle stimulation at a temperature of 43? and a period of 45 min insertion of the needle without heating served as control,after treatment 3 days,rats were sacrificed respectively and get the joint effusion and blood.In sub-experiment 2,ELISA method was used to detect the expression of IL-1 in articular cavity effusion and the expression of PGE2 was detected by radioimmunoassay.Results1.Compared with 0.9%saline group and 0.9%saline + Tween80 group,the threshold of mechanical responses of injection side in urate group was significantly lower in 1-5 days(P<0.05).The bilateral heat pain threshold of the urate group was significantly higher than that of the 0.9%saline group and the 0.9%saline +Tween80 group(P<0.05),and the swelling degree of the injection side of the urate group was significantly higher than that of the other two groups,with statistical significance(P<0.05).2.Compared with urate group,a period of 15-45 min ipsilateral i.m.43?heating-needle stimulation failed to cause any effects on bilateral mechanically evoked paw withdrawal reflexes,whereas prolonged bilateral heat-evoked paw withdrawal latencies(heat hypoalgesia)were significantly observed.The swelling degree of ankle joint was statistically significant(P<0.05).Significantly enhanced mechanically evoked responses(mechanical hyperalgesia)were found following the 15-45 min of i.m.46? heating-needle stimulation.Heat hypoalgesia after the i.m.46? heating-needle stimulation were as same as i.m.43? heating-needle stimulation.There was no significant difference in the degree of swelling of the ankle joint after the different treatments(P>0.05).3.There was no significant difference between the i.m.43? and 46?heating-needle applied to ' Zusanli ' acupoint stimulation ipsilaterally and contralaterally which in therapeutic effect on acute pain induced by intra-articular injection of urate.4.There was no significant difference in the mechanical stimulation between the different receptor antagonists of the intrathecal opioid receptor antagonists in the urate group and the 0.9%saline group(P>0.05).The bilateral heat hypoalgesia was significantly decreased by the i.t.microinjection of ?-opioid receptor antagonist ?-FNA,?-opioid receptor antagonist naltrindole,whereas ?-opioid receptor antagonists nor-BNI had no effects.5.In Urate + N.S.45 min group,the number of 1L-1 in the joint effusion and PGE2 in the blood were lower than the urate group,but there was no significant difference.In Urate + warm N.S.30 min group,the number of 1L-1 in the joint effusion and PGE2 in the blood compared with the urate group was statistically significant(P<0.05).Conclusion1.Intra-articular injection of urate effctively can produce the inflammatory effects,mechanical hyperalgesia and heat hypoalgesia were decreased and the joint swelling was found in the rats,in accordance with the clinical symptoms of arthritis in patients with gout attack.2.The i.m.43? heating-needle stimulation significantly inhibit pathological mechanical hyperalgesia and enhance heat hypoalgesia during the condition of intra-articular injection of urate induced arthritis.The i.m.46? heating-needle stimulation can enhance mechanical hyperalgesia.In addition,the i.m.43?,but not 46?,heating-needle stimulation has significant anti-swelling effect.3.Heating-needle applied to 'Zusanli' acupoint stimulation on ipsilateral and contralateral side both active the inhibition the pathological pain by urate induced arthritis.Left disease-right treatment support the clinical usage in treating inflammatory pain.4.Heating-needle acupoint stimulation can be through opioid receptors in the spinal cord of different types to relieve acute gouty arthritis.